Electrical conductivity of multilayer monopolar ion-exchange membranes

Abstract

The paper presents the results of measurements of electrical resistivity of multilayer ion-exchange membranes. For the measurement of electrical resistance has been applied to cell, in which between the electrodes was placed a package ion-exchange membranes. The membranes in the conductivity cell were in equilibrium with the pure water to prevent the ingress of non-exchanged sorbed electrolyte. The design of the cell allowed thermostating membranes and pure water. To measure the impedance meter was used LCR HITESTER HIOKI, which allows the values of the impedance to allocate its components-the active electrical resistance, capacitance and inductance. The results showed that intermembrane electrical resistivity is significantly lower than the electrical resistivity of the membranes themselves and the boundaries of the electrode-membrane. This proves the correctness of the contact-difference method for measuring the electrical conductivity of membranes, which consists in finding the difference between the electrical resistance of n+1 and n membranes. The work also contains the results of measurements of specific electrical conductivity of heterogeneous cation exchange membranes MK-40 and anion exchange membranes MA-41 in the low frequencies of alternating current. Extrapolation of values of specific electrical conductivity of ion-exchange membranes to zero frequency allowed to determine electrical conductivity of membranes close to their values at constant current. Since electrodialysis with ion-exchange membranes is carried out at a constant current, such values are necessary for calculating the electrical parameters of electro-membrane processes and in formulating the boundary conditions of the boundary value problems of periodic and continuous electrodialysis kinetics with alternating cation-exchange and anion-exchange membranes.